FAIR VALUES OF FINANCIAL INSTRUMENTS - Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Assets:
Cash and due from banks	$ 84,719	$ 112,649
Interest-bearing deposits	359,126	436,080
Investment securities available for sale	1,553,496	1,627,112
Investment securities held to maturity, net	1,823,006	1,870,374
Loans held for sale	40,652	18,934
Net loans	12,251,924	11,958,301
Federal Home Loan Bank stock	41,716	41,769
Derivative assets	62,270	79,379
Interest receivable	92,055	97,664
Liabilities:
Deposits	14,361,346	14,811,957
Borrowings:
Federal funds purchased	30,000
Securities sold under repurchase agreements	124,894	157,265
Federal Home Loan Bank advances	841,458	707,377
Subordinated debentures and other borrowings	83,242	149,995
Deposits and other liabilities held for sale	266,898
Derivative liabilities	61,386	79,008
Interest payable	18,089	18,912
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and due from banks	84,719	112,649
Interest-bearing deposits	359,126	436,080
Investment securities available for sale	0	0
Investment securities held to maturity, net	0	0
Loans held for sale	0	0
Net loans	0	0
Federal Home Loan Bank stock	0	0
Derivative assets	0	0
Interest receivable	0	0
Liabilities:
Deposits	11,980,746	12,482,295
Borrowings:
Federal funds purchased	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Deposits and other liabilities held for sale	0
Derivative liabilities	0	0
Interest payable	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	1,551,015	1,623,802
Investment securities held to maturity, net	1,815,856	1,859,974
Loans held for sale	40,652	18,934
Net loans	0	0
Federal Home Loan Bank stock	41,716	41,769
Derivative assets	62,270	79,379
Interest receivable	92,055	97,664
Liabilities:
Deposits	2,380,600	2,329,662
Borrowings:
Federal funds purchased	30,000
Securities sold under repurchase agreements	124,894	157,265
Federal Home Loan Bank advances	841,458	707,377
Subordinated debentures and other borrowings	83,242	149,995
Deposits and other liabilities held for sale	266,898
Derivative liabilities	61,386	79,008
Interest payable	18,089	18,912
Significant Unobservable Inputs (Level 3)
Assets:
Cash and due from banks	0	0
Interest-bearing deposits	0	0
Investment securities available for sale	2,481	3,310
Investment securities held to maturity, net	7,150	10,400
Loans held for sale	0	0
Net loans	12,251,924	11,958,301
Federal Home Loan Bank stock	0	0
Derivative assets	0	0
Interest receivable	0	0
Liabilities:
Deposits	0	0
Borrowings:
Federal funds purchased	0
Securities sold under repurchase agreements	0	0
Federal Home Loan Bank advances	0	0
Subordinated debentures and other borrowings	0	0
Deposits and other liabilities held for sale	0
Derivative liabilities	0	0
Interest payable	0	0
Carrying Amount
Assets:
Cash and due from banks	84,719	112,649
Interest-bearing deposits	359,126	436,080
Investment securities available for sale	1,553,496	1,627,112
Investment securities held to maturity, net	2,108,649	2,184,252
Loans held for sale	40,652	18,934
Net loans	12,458,980	12,281,093
Federal Home Loan Bank stock	41,716	41,769
Derivative assets	62,270	79,379
Interest receivable	92,055	97,664
Liabilities:
Deposits	14,365,100	14,821,453
Borrowings:
Federal funds purchased	30,000
Securities sold under repurchase agreements	124,894	157,280
Federal Home Loan Bank advances	832,629	712,852
Subordinated debentures and other borrowings	93,562	158,644
Deposits and other liabilities held for sale	288,476
Derivative liabilities	61,386	79,008
Interest payable	$ 18,089	$ 18,912

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Fair value portion of deposit liabilities held by the entity, including, but not limited to, foreign and domestic, interest and noninterest bearing, demand deposits, saving deposits, negotiable orders of withdrawal (NOW) and time deposits.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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